A vibration felt at 55 mph may not be a tire problem. Mazda has revised motor mounts available which may help remedy this problem.
A loose rear stabilizer bar link can cause a rattling noise from the rear suspension while driving on rough roads. Our technicians tell us if the rear stabilizer bar and links are not found to be loose, there are updated sway bar bushings available which should correct this problem.
The rear brakes can squeak because the rear brake pad may be contacting the brake rotor . A burr on the backing plate of the brake pad can prevent the pad from seating in the bracket properly causing the contact with the rotor. The backing plate and the pad support hardware can be deburred in the contact areas. Mazda has also released revised brake pads.